If not using gas grill, light coals (30-40), while coals are cooking, put ground beef ino large bowl, add garlic powder & 1/2 cup salsa. mix together and place in fridge. Once coals are ready place whole chili's on grill, roast until blackened about 10mins. (if canned skip this step) remove from fire and place in paper bag, close and set aside. Prepare sause: put mayo & remaining salsa in small bowl, stir and put in fridge. remove ground beef from fridge and make into 6 patties, place on platter. Get out cheese, if not sliced, slice into 24 slices and place on platter. Slice and butter buns, place on plater. Remove 6 chili's from bag, peel/remove skins, split in half and remove seeds and stems. put on platter. ( if canned remove from can, spit and remove seeds). Remove patties from fridge, gentle place over fire. DO NOT flatten or move patties. leave for 5 mins till char'd. gentle flip on other side, 5 mins DO NOT touch. Take platter out to grill. When burgers are done move aside of direct heat, placing 2 slices of cheese on each burger then top cheese with one whole green chili and top green chili with 2 more slices of cheese, shut lid. Once cheese begins to melt, then put buns - butter side down until toasted. when buns have toasted remove burgers and place on buns. Apply sause and serve